Achazyah son of Achav reigned over Israel in the year 3041, the 17th year of Yehoshafat, and he reigned for two cut-short years. And if they had been two complete years, the beginning of the reign of Yehoram his brother should have been in the 19th year of Yehoshafat, but the verse says that Yehoram reigned in the 18th year of Yehoshafat. And know that all the commentators were troubled, for according to calculation Achazyah should have reigned in the 18th year of Yehoshafat, because in the 4th year of Achav Yehoshafat reigned, and Achav reigned for 22 years, so Achav reigned after the 4th year, which is the beginning of Yehoshafat's reign, for another 18 years—so all the days of Achav were in the 18th year of Yehoshafat, not the 17th year.

And furthermore, the 4 years of Achav were cut-short as explained above, and for the kings of Yehuda they are not counted, so according to this all the days of Achav were in the 19th year of Yehoshafat. But it has already been explained that the way of Scripture in some of the lacking years is to count them as complete years [(Tzemach David) (see above year 2964, and see Rashi Melachim 1 22:51)]. And he did evil [(Melachim 1 22:51)].